diff --git a/src/native/build.xml b/src/native/build.xml
index ab162cc25..4bd24feb0 100644
--- a/src/native/build.xml
+++ b/src/native/build.xml
@@ -377,8 +377,7 @@
       <!-- Windows specific flags -->
       <compilerarg value="-I${system.JAVA_HOME}/include" if="is.running.windows" />
       <compilerarg value="-I${system.JAVA_HOME}/include/win32" if="is.running.windows" />
-      <compilerarg value="-I${pthread}" if="is.running.windows" />
-      
+
       <linkerarg value="-L${pthread}" if="is.running.windows" />
       <linkerarg value="-ojportaudio.dll" if="is.running.windows" />
       <linkerarg value="-Wl,--kill-at" if="is.running.windows" />
@@ -387,7 +386,6 @@
       <linkerarg value="-lspeexdsp" location="end" if="is.running.windows" />
       <linkerarg value="-lwinmm" location="end" if="is.running.windows" />
       <linkerarg value="-lm" location="end" if="is.running.windows" />
-      <linkerarg value="-lpthreadGC2" location="end" if="is.running.windows" />
       <linkerarg value="-lstdc++" location="end" if="is.running.windows" />
       <linkerarg value="-lole32" location="end" if="is.running.windows" />
       <linkerarg value="-luuid" location="end" if="is.running.windows" />
@@ -595,7 +593,6 @@
     <echo message="-Dffmpeg: path to ffmpeg directory (ffmpeg JNI compilation)." />
     <echo message="-Dportaudio path to portaudio directory (jportaudio JNI compilation)." />
     <echo message="-Dspeex: path to speex directory (jportaudio/jspeex JNI compilation)." />
-    <echo message="-Dpthread: path to pthread directory (Windows only). If you already have pthread in MinGW don't use it." />
     <echo message="" />
     <echo message="Please note that external libraries such as ffmpeg, x264, portaudio and speex have to be compiled" />
     <echo message="(follow READMEs in relevant directory) before trying to compile libffmpeg and libjportaudio"  />
diff --git a/src/native/portaudio/AudioQualityImprovement.c b/src/native/portaudio/AudioQualityImprovement.c
index 60ac9c679..157f29d6c 100644
--- a/src/native/portaudio/AudioQualityImprovement.c
+++ b/src/native/portaudio/AudioQualityImprovement.c
@@ -34,8 +34,14 @@ static void AudioQualityImprovement_setFrameSize
 static void AudioQualityImprovement_updatePreprocess
     (AudioQualityImprovement *audioQualityImprovement);
 
+#ifndef _WIN32
 static pthread_mutex_t AudioQualityImprovement_sharedInstancesMutex
     = PTHREAD_MUTEX_INITIALIZER;
+#else /* Windows */
+static CRITICAL_SECTION AudioQualityImprovement_sharedInstancesMutex = {0};
+static int initialized = 0;
+#endif
+
 static AudioQualityImprovement *AudioQualityImprovement_sharedInstances
     = NULL;
 
@@ -70,7 +76,7 @@ static void
 AudioQualityImprovement_free(AudioQualityImprovement *audioQualityImprovement)
 {
     /* mutex */
-    pthread_mutex_destroy(audioQualityImprovement->mutex);
+    mutex_destroy(audioQualityImprovement->mutex);
     free(audioQualityImprovement->mutex);
     /* preprocess */
     if (audioQualityImprovement->preprocess)
@@ -98,7 +104,15 @@ AudioQualityImprovement_getSharedInstance(const char *stringID, jlong longID)
 {
     AudioQualityImprovement *theSharedInstance = NULL;
 
-    if (!pthread_mutex_lock(&AudioQualityImprovement_sharedInstancesMutex))
+#ifdef _WIN32
+    if(!initialized)
+    {
+        mutex_init(&AudioQualityImprovement_sharedInstancesMutex, NULL);
+        initialized = 1;
+    }
+#endif
+
+    if (!mutex_lock(&AudioQualityImprovement_sharedInstancesMutex))
     {
         AudioQualityImprovement *aSharedInstance
             = AudioQualityImprovement_sharedInstances;
@@ -126,7 +140,7 @@ AudioQualityImprovement_getSharedInstance(const char *stringID, jlong longID)
             if (theSharedInstance)
                 AudioQualityImprovement_sharedInstances = theSharedInstance;
         }
-        pthread_mutex_unlock(&AudioQualityImprovement_sharedInstancesMutex);
+        mutex_unlock(&AudioQualityImprovement_sharedInstancesMutex);
     }
     return theSharedInstance;
 }
@@ -156,9 +170,9 @@ AudioQualityImprovement_new
             return NULL;
         }
         /* mutex */
-        audioQualityImprovement->mutex = malloc(sizeof(pthread_mutex_t));
+        audioQualityImprovement->mutex = malloc(sizeof(Mutex));
         if (!(audioQualityImprovement->mutex)
-                || pthread_mutex_init(audioQualityImprovement->mutex, NULL))
+                || mutex_init(audioQualityImprovement->mutex, NULL))
         {
             AudioQualityImprovement_free(audioQualityImprovement);
             return NULL;
@@ -186,7 +200,7 @@ void AudioQualityImprovement_process
 {
     if ((sampleSizeInBits == 16)
             && (channels == 1)
-            && !pthread_mutex_lock(audioQualityImprovement->mutex))
+            && !mutex_lock(audioQualityImprovement->mutex))
     {
         switch (sampleOrigin)
         {
@@ -228,7 +242,7 @@ void AudioQualityImprovement_process
             }
             break;
         }
-        pthread_mutex_unlock(audioQualityImprovement->mutex);
+        mutex_unlock(audioQualityImprovement->mutex);
     }
 }
 
@@ -236,9 +250,9 @@ void
 AudioQualityImprovement_release
     (AudioQualityImprovement *audioQualityImprovement)
 {
-    if (!pthread_mutex_lock(&AudioQualityImprovement_sharedInstancesMutex))
+    if (!mutex_lock(&AudioQualityImprovement_sharedInstancesMutex))
     {
-        if (!pthread_mutex_lock(audioQualityImprovement->mutex))
+        if (!mutex_lock(audioQualityImprovement->mutex))
         {
             --(audioQualityImprovement->retainCount);
             if (audioQualityImprovement->retainCount < 1)
@@ -269,13 +283,13 @@ AudioQualityImprovement_release
                     }
                 }
 
-                pthread_mutex_unlock(audioQualityImprovement->mutex);
+                mutex_unlock(audioQualityImprovement->mutex);
                 AudioQualityImprovement_free(audioQualityImprovement);
             }
             else
-                pthread_mutex_unlock(audioQualityImprovement->mutex);
+                mutex_unlock(audioQualityImprovement->mutex);
         }
-        pthread_mutex_unlock(&AudioQualityImprovement_sharedInstancesMutex);
+        mutex_unlock(&AudioQualityImprovement_sharedInstancesMutex);
     }
 }
 static void
@@ -364,10 +378,10 @@ static void
 AudioQualityImprovement_retain
     (AudioQualityImprovement *audioQualityImprovement)
 {
-    if (!pthread_mutex_lock(audioQualityImprovement->mutex))
+    if (!mutex_lock(audioQualityImprovement->mutex))
     {
         ++(audioQualityImprovement->retainCount);
-        pthread_mutex_unlock(audioQualityImprovement->mutex);
+        mutex_unlock(audioQualityImprovement->mutex);
     }
 }
 
@@ -375,14 +389,14 @@ void
 AudioQualityImprovement_setDenoise
     (AudioQualityImprovement *audioQualityImprovement, jboolean denoise)
 {
-    if (!pthread_mutex_lock(audioQualityImprovement->mutex))
+    if (!mutex_lock(audioQualityImprovement->mutex))
     {
         if (audioQualityImprovement->denoise != denoise)
         {
             audioQualityImprovement->denoise = denoise;
             AudioQualityImprovement_updatePreprocess(audioQualityImprovement);
         }
-        pthread_mutex_unlock(audioQualityImprovement->mutex);
+        mutex_unlock(audioQualityImprovement->mutex);
     }
 }
 
@@ -393,7 +407,7 @@ AudioQualityImprovement_setEchoFilterLengthInMillis
 {
     if (echoFilterLengthInMillis < 0)
         echoFilterLengthInMillis = 0;
-    if (!pthread_mutex_lock(audioQualityImprovement->mutex))
+    if (!mutex_lock(audioQualityImprovement->mutex))
     {
         if (audioQualityImprovement->echoFilterLengthInMillis
                 != echoFilterLengthInMillis)
@@ -402,7 +416,7 @@ AudioQualityImprovement_setEchoFilterLengthInMillis
                 = echoFilterLengthInMillis;
             AudioQualityImprovement_updatePreprocess(audioQualityImprovement);
         }
-        pthread_mutex_unlock(audioQualityImprovement->mutex);
+        mutex_unlock(audioQualityImprovement->mutex);
     }
 }
 
@@ -421,14 +435,14 @@ void
 AudioQualityImprovement_setSampleRate
     (AudioQualityImprovement *audioQualityImprovement, int sampleRate)
 {
-    if (!pthread_mutex_lock(audioQualityImprovement->mutex))
+    if (!mutex_lock(audioQualityImprovement->mutex))
     {
         if (audioQualityImprovement->sampleRate != sampleRate)
         {
             audioQualityImprovement->sampleRate = sampleRate;
             AudioQualityImprovement_updatePreprocess(audioQualityImprovement);
         }
-        pthread_mutex_unlock(audioQualityImprovement->mutex);
+        mutex_unlock(audioQualityImprovement->mutex);
     }
 }
 
diff --git a/src/native/portaudio/AudioQualityImprovement.h b/src/native/portaudio/AudioQualityImprovement.h
index fb9d095a3..176d850b3 100644
--- a/src/native/portaudio/AudioQualityImprovement.h
+++ b/src/native/portaudio/AudioQualityImprovement.h
@@ -13,7 +13,65 @@
 #ifndef AUDIO_QUALITY_IMPROVEMENT_IMPLEMENTATION
 typedef void *AudioQualityImprovement;
 #else /* #ifndef AUDIO_QUALITY_IMPROVEMENT_IMPLEMENTATION */
+
+#ifdef _WIN32
+#define WIN32_LEAN_AND_MEAN
+#include <windows.h>
+
+typedef CRITICAL_SECTION Mutex;
+
+static inline int mutex_init(Mutex* mutex, void* arg)
+{
+    InitializeCriticalSection(mutex);
+    arg = NULL; /* unused */
+    return 0;
+}
+
+static inline int mutex_destroy(Mutex* mutex)
+{
+    DeleteCriticalSection(mutex);
+    return 0;
+}
+
+static inline int mutex_lock(Mutex* mutex)
+{
+    EnterCriticalSection(mutex);
+    return 0;
+}
+
+static inline int mutex_unlock(Mutex* mutex)
+{
+    LeaveCriticalSection(mutex);
+    return 0;
+}
+
+#else /* Unix */
 #include <pthread.h>
+
+typedef pthread_mutex_t Mutex;
+
+static inline int mutex_init(Mutex* mutex, void* arg)
+{
+    return pthread_mutex_init(mutex, arg);
+}
+
+static inline int mutex_destroy(Mutex* mutex)
+{
+    return pthread_mutex_destroy(mutex);
+}
+
+static inline int mutex_lock(Mutex* mutex)
+{
+    return pthread_mutex_lock(mutex);
+}
+
+static inline int mutex_unlock(Mutex* mutex)
+{
+    return pthread_mutex_unlock(mutex);
+    return 0;
+}
+#endif
+
 #include <speex/speex_echo.h>
 #include <speex/speex_preprocess.h>
 #include <speex/speex_resampler.h>
@@ -27,7 +85,7 @@ typedef struct _AudioQualityImprovement
     jint frameSize;
     int frameSizeOfPreprocess;
     jlong longID;
-    pthread_mutex_t *mutex;
+    Mutex *mutex;
     struct _AudioQualityImprovement *next;
     spx_int16_t *out;
     spx_uint32_t outCapacity;
diff --git a/src/native/windows/directshow/net_java_sip_communicator_impl_neomedia_directshow_DSCaptureDevice.cpp b/src/native/windows/directshow/net_java_sip_communicator_impl_neomedia_directshow_DSCaptureDevice.cpp
index dfa2ae871..a9ab07a4d 100644
--- a/src/native/windows/directshow/net_java_sip_communicator_impl_neomedia_directshow_DSCaptureDevice.cpp
+++ b/src/native/windows/directshow/net_java_sip_communicator_impl_neomedia_directshow_DSCaptureDevice.cpp
@@ -98,6 +98,11 @@ public:
                 sample->GetPointer(&data);
                 length = sample->GetActualDataLength();
 
+                if(length == 0)
+                {
+                    return S_OK;
+                }
+
                 if(!m_bytes || m_bytesLength < length)
                 {
                     if(m_bytes)